1. Technical Field
The inventive arrangements relate generally to video systems and more particularly to video systems that record or play back digitally encoded video sequences.
2. Description of Related Art
Devices that facilitate the playback of video are gaining popularity in today's consumer electronics marketplace. For example, many consumers have purchased digital video disc (DVD) recorders or players for purposes of viewing previously recorded programs or recording their favorite programs. A DVD recorder or player typically contains a Moving Pictures Expert Group (MPEG) decoder to decode the digitally encoded multimedia data that is stored on the discs that the recorder or player plays. The MPEG video signal to be decoded is comprised of a plurality of groups of pictures (GOP), each of which typically contain an intra (I) picture, a plurality of predictive (P) pictures and a plurality of bidirectional predictive (B) pictures.
If the digital video recorder or player is connected to certain televisions, the digitally encoded signal will be decoded by the digital video recorder or player's MPEG decoder before being displayed on the television. Significantly, however, many digital televisions (DTV) contain their own MPEG decoders. As such, if a digital video recorder or player is connected to a DTV, the video signal read from the disc is remotely decoded by the DTV's decoder. This type of decoder is considered a passive decoder in that the microprocessor in the digital video recorder or player has no control over the decoder. This configuration can be referred to as a remote decoder system.
During playback of a video signal, some viewers may wish to perform certain trick modes. A trick mode can be any playback of video in which the playback is not done at normal speed or in a forward direction. As an example, a reverse trick mode can be initiated to allow the viewer to locate portions of video that have already been played and that the viewer may wish to view again. The reverse trick mode can be at a normal speed or pictures in a GOP may be skipped to produce a fast-reverse trick mode. In addition, duplicates of the pictures in a GOP may be inserted in the GOP to generate a slow-reverse trick mode. To effectuate a reverse trick mode on an MPEG video signal, the decoder of the DVD may decode the pictures in a GOP in a forward direction. Once these pictures are decoded, the decoder is instructed to display the pictures in reverse order and if necessary, to add duplicate pictures to the GOP or to skip pictures in the GOP.
A remote decoder system, however, is not particularly suited to perform reverse trick modes. The reason for this drawback is that the microprocessor of the digital video recorder or player cannot instruct the decoder to display the pictures in reverse. As such, a reverse trick mode in such an arrangement is typically limited to merely sending to the decoder in a reverse order the I pictures in all or some of the GOPs of the video signal.